The broad interest in epoxy resins originated from their excellent adhesion to a variety of materials, shelf-life stability of the uncatalyzed liquid resin alone, and electrical and physical properties of the cured laminates. Depending upon the structure of the curing agent and curing conditions, it is possible to obtain toughness, chemical resistance and mechanical properties ranging from extreme flexibility to high strength hardness, high adhesive strength, good heat resistance and high electrical insulation. The art of utilizing high-strength fibers with good adhesive properties of epoxy resins in producing superior composite materials is well known. The known uses of the efficient high strength-to-weight ratio are in the air frame industry, for marine vessels, and other transportation industries, for electrical insulation, chemical processing tanks and building construction. Epoxy-fabric or fiber laminates have been used in many stages of the fabrication of aircraft because of their simplicity of fabrication, light weight, low cost and low radar echo. For many purposes, graphite cloth has been gaining favor over fiberglass cloth for composite use because of its lighter weight and high tensile and elastic modulus values. In recent years, with increasing concern for human survivability against fire hazards, many polymeric materials such as polyimides, modified phenolics, bismaleimides and including many epoxy resin systems were studied as matrix resins. The dynamic thermogravimetric analyses and the limiting oxygen index were the two main experimental techniques used to evaluate the flammability properties of these materials. Based on these studies, the epoxy based resins are rated as poor in respect to their thermal stability and flammability. In general, polymers with high anaerobic char yields are expected to show high limiting oxygen index (LOI) and low flammability. The incorporation of the highly aromatic structure of the metal phthalocyanines into polymers is known to increase thermal stability and the chemical resistance. The use of the phthalocyanine carboxylic acids and copper phthalocyanine to cure epoxy resins has been described in U.S. Pat. No. 3,301,814 (Jan. 31, 1967) and shown to incorporate good thermal stability and good adhesion to stainless steel at high temperature. However, those phthalocyanine derivatives and copper phthalocyanine are insoluble, react heterogeneously and remained as discrete particles even after curing. Because of this major disadvantage of insolubility, complete realization of their thermal stability and chemical resistance of the phthalocyanines were not seen in the cured resins.
In our copending application, Ser. No. 440,656 polymers of metal (II) 4,4',4",4'"-phthalocyanine tetraamines with various dianhydrides are described.